Multiband inductance unit



Nov. 30, 1937. LYONS 2,100,402

-MULT IBAND INDUCTANCE UNIT Filed Jan. 10, 1936 a DETECTOR 4- K c.

INVENTOR. ALTER LYONS.

ATTORNEY.

Patented Nov. 30, 1937 MULTIBAND INDUCTANCE UNIT Walter Lyons, Flushing, N. Y., assignor to Hazeltine Corporation, a corporation of Delaware Application-January 10, 1936, Serial No. 58,468 6 Claims. (01. 250-40) ticular between receivers manufactured at a com-- mon source but destined for different distribu- 15 tors in the same market, and between receivers manufactured at a common source but destined for difierent markets. It has been a-common practice, notwithstanding the identity of a considerable portion of the apparatus of such re- 20 ceivers, to manufacture and stock complete receivers forjeach different set of frequency bands. Further, the manufacture of multi-band receivers to a given production standard has been difficult due to the limited tolerances ordinarily per- 3 mitted in the assembly and wiring of such receivers. This is particularly true in the higher frequency bands, where small deviations in the length and/or placement of the leads to the tuned circuit elements cause substantial deviations in the'responses of such tuned circuits.

It is an object of thisinvention to eliminate the duplication entailed by the manufacturing practice mentioned above, to enable multi-band receivers to be manufactured readily and closely to'a given production standard, to reduce the number of complete receivers that the manufacturer must carry in stock, to reduce the losses resulting from unsold receivers and to simplify the manufacture of different receivers having consid- 4- erable identical equipment.

It is a further object of this invention to provide a compact, readily accessible,..readily adiustable andinterchangeable multi-band induct-' ance unit including the various inductance ele- 43 ments'and associated apparatus, such as bandselecting switches and trimmer condensers, in which elements the differences between two or more otherwise identical multi-band receivers normally obtain. As a consequence, the manu- 50 facturer may, make up and stock a single receiver chassis, minus the multi-band inductance unit, forall such receivers, may .make up and stock such units for each of the different sets of frequency bands for which it isv desired to de- 5 sign a receiver, and thus, may quickly and easily fill orders for receivers operative over any particular set of bands by equipping the chassis.

with multi-band inductance units corresponding to sueh particular set of bands. In addition, due 60 to the use of the multi-band inductance unit, the

completed receivers adhere closely to the production standard, particularly as to alignment and band coverage.

Other objects of the invention will become apparent when considering the following specl- 5 fication, taken in conjunction with the accompanying drawing and the appended claims.

A preferred embodiment of the invention contemplates a multi-band inductance unit consisting of the inductances for all the tunable stages of the receiver, the inductances for each of the several stages being formed into an assembly, as by winding them on a common form. The term tunable stage is used herein to denote any tunable system of a receiver such as a tunable radio-frequency selector or a tunable frequencydetermining circuit of an oscillator or oscillatormodulator. The inductance assemblies are mounted upon a supporting structure which also supports a rotary switch. This switch has groups 0 of contacts individual to the several tunable stages of the receiver, the groups of contacts being disposed about the operating shaft of the switch. The several inductance assemblies are so disposed on the supporting structure that terminals provided on such assemblies are proximate to their respective switch contacts. The interconnecting leads between the inductance assembly terminals and the switch contacts may thus be short and linear. The entire unit is arranged to be detachably mounted upon a suitable sup porting panel. The inductance assemblies are usually enclosed within shield cans which are also mounted 'upon the supporting structure. When the inductance assemblies are provided with trimmer condensers, these are preferably mounted within the respective shield cans with access to their adjusting screws provided through suitable apertures in the shield cans. Inorder that such access may be had after the unit is in- 40 stalled in areceiver, the shield cans are mounted in "a staggered relationship upon the supporting structure with all the adjusting screw apertures facing in the same direction.

In the drawing, Fig. 1 is a circuit diagram,

partly schematic, of a multi-band superheterodyne receiver to which the invention is particularly applicable; Fig. 2 is a view in elevation of a multi-band inductance unit embodying the invention; Fig. 3 is a view of the unit taken along the section line 3-3 of Fig. 2; Fig. 4 is a view of .the unit taken along the section line 4'4 of Fig.

2; andFig. 5 is a view of the unit taken along the section line55 of Fig. 2.

Referring vto Fig. 1, the multi-band superheterodyne receiver there shown comprises an antenna j circuit In, with an intermediate-frequency trap circuit H therein, connected through coupling condenser l2 to the multi-band selector circuit I 3 9f the first tunable stage of the receiver. Circuit 6o l3 includes a primary inductance element I4,

three series connected secondary inductance elements I5, I8, and I1 inductively related to the primary element l4, and a variable tuning condenser |8 connected across the exterior terminals of the series connected inductances, the low potential side of condenser l8 being connected to the low potential terminal of inductance element" 5 through a coupling condenser 28. Three adiustably fixed trimmer condensers 2|,22 and 23 are connected in parallel with inductance elements l5, l6 and II, respectively. Inductance elements l5 and I6 may be selectively short-circuited by a band-selecting switch 24 so as selectively to connect the inductance elements l5, I8 and I I effectively in circuit with variable condenser,l8 for causing the first tunable stage of the receiver. to operate over the several frequency bands.

A vacuum tube 25 serving as a radio-frequency amplifier is connected to the selector circuit 3, the anode of such tube being connected to the primary'inductance element.3| of the selector circuit 38 of the second tunable stage of the re: ceiver. This circuit 38 has series-connected secondary inductance elements 32, 33 and 34:, parallel trimmer condensers 35, 38 and 31, a variable tuning condenser 38, a band-selecting switch 49 and a coupling and series-aligning condenser 4| arranged and connected in the same manner as the corresponding elements in the first tunable stage of the receiver. The selector circuit 39 is connected to the modulator grid of a vacuum tube 44 serving as an oscillator-modulator.

The third tunable stage of the receiver includes the oscillation circuit 45 for tube 44, circuit 45 prising three series-connected secondary inductance elements 48, 41 and 48, parallel trimmer condensers 58, 5| and 52, a variable tuning condenser 53 and a band-selecting switch 54 arranged and connected in the same manner as the corresponding elements in the first and second tunable The low potential terminal of inductance stages. element '46 is connected to the low potential side of variable condenser 53 through coupling and series-aligning condensers 55 and 58 in series, the condenser 58 acting alone in aligning in the highfrequency range and the two condensers 55 and 58 acting together in the low-frequency range..

In the middle-frequency range condenser 58 acts alone as a coupling condenser, and as an aligning condenser in conjunction with acondenser 51 which is then effectively connected in series therewith by the band-selecting switch 54.

The .oscillation-producing coupling, or feedback, for oscillation circuit 45 is provided by two the dotted line 83. Band-selecting switches 24,- 48 and 54 are also preferably ganged for unicon trol', as indicated by the dotted line 64. Suitable 8| 82 and 83 for the several circuits, as schematically illustrated in Fig. 1.

In cascade with oscillator-modulator 44 are an intermediate-frequency amplifier 84, a detector and automatic amplification control source 85, an audio-frequency amplifier 88 and a sound reproducer 81. The automatic amplification control bias potential (A. V. C.) may be applied to anyone or more of the radio-frequency amplifier tube 25, the oscillator-modulator tube 44 and the intermediate-frequency amplifier 84'as desired. The automatic amplification control connection to the oscillator-modulator tube 44 includes a filter comprising high resistance element 88 and condenser 4|, while that to the amplifier tube, 25 includes a filter comprising high resistor 89 and condenser 29.

In operation, the desired received signal is selected in selector circuit I3, is amplified in tube 25, is further selected by the selector circuit 30 and transferred to the oscillator-modulator tube 44 where the signabis converted into a modulated intermediate frequency. The signal, as thus converted, is amplified in the intermediate-frequency amplifier 84 and rectified by detector 85, producingthe audio frequencies of modulation, which are amplified in the audio-frequency amplifier 86 and reproduced by the sound reproducer 81.

The amplificationof the received signal is subjebt to automatic control by the A. v. c. bias potentials, according to the manner well understood in the art, to maintain the signal output of the receiver within a relatively narrow range for a wide range of amplitudes of received signals.

The interchangeable multi-band inductance unit 98 for the receiver is a unit formed of the followingapparatus shown in Fig. l: the inductanoe elements of the tunable circuits 3, 38 and 45 and their respective trimmer condensers, shield cans, and band-selecting switches. In addition, the unit may include various condensers.

and resistances which are electrically'proximate and related to the preceding apparatua for example, condensers 85, 4|, 66, 55, 56 and 51 and resistors 88 and 89.

Referring now to Figs. 2-5 whichillustrate a preferred construction of the multi-band inbetween the formand the shield can. Mounted along strip 93 are the trimmer condensers 2|, 22

and 23, with the adjusting screw of each facing upwardly, as viewed in Fig. 2, the shield can 8| 'being suitably apertured or cut away as at 94,

above the adjusting screws, so that access may be had thereto. Shield can 8| has two lugs 95 suitably attached thereto at one end which extend through a supporting and shielding plate 98 and serve to mount thereon the shield can 8|, its inductance elements and their trimmer condensers, with he axis of form 9|, and longitudinal axis of the shield can 8|, perpendicular thereto. The form 9| has suitable inductance element terminals 91 mounted thereon at each end. The terminals preferably extend beyond the open ends of the shield can 8|, shield plate .96 having an aperture 98 therein for the set of terminals 9] at the supported end of the shield can.

The corresponding apparatus for the other two tunable stages of the receiver are assembled and mounted in a manner similar to that described for the first tunable stage. A detailed description of the mounting and arrangement of such apparatus for the other two tunable stages is thus unnecessary.

The shield cans iii, 82 and83-are mounted on shield plate 96 so that the adjusting screws for all of the trimmer condensers and the apertures of their respective shield cans face in the same direction.

The three shield cans are also mounted on shield plate 96 in staggered relationship so that the adjusting screws for all trimmer condensers may be reached by access to a single side of the unit. In the unit illustrated, the three shield cans are at the vertices of a substantially equilateral triangle, with the adjusting screws for all the trimmer condensers facing a plane which is parallel to the longitudinal axes of the shield cans and to one side of the triangle. In addition, the shield cans are so proportioned that there is substantial clearance between cans 8| and 83 through which access maybe had to the adjusting screws for the trimmer condensers within shield can 82.

The band-selecting switches 24, 40 and 54.

of Fig. 1 are incorporated in a rotary switch I05 secured, as by the bolts I06, to the shield plate 96 on the opposite side from the shield cans. Ro-

tary switch I05 is preferably a single deck switch.

- in order to reduce the over-all length of the unit,

with the plane of its switch body I01 parallel to the plane of the shield plate 96, and is provided with a switch actuating shaft I 08 the axis I of which extends perpendicularly to the plane of switch body I01. The switch is preferably so positioned relative to the axes of forms 9| that the axis I00 is substantially equidistant from v such axes. The contacts of the switch are preferably so arranged, as in the unit illustrated, that the terminals of the switch contacts 24a, 24b and No of the band-selecting switch 24, of the switch contacts 40a, 40b and40c of the band-selecting switch 40 and of the switch contacts 54a, 54b and 540 of the band-selecting switch 54, are proximate to the terminals of the inductance assemblies with which they are respectively associated and which extend through the shield plate 96. The connecting leads I09 between the inductance assembly terminals 91 and their respective switch contact terminals are thus short and substantially linear.

The contact structure of rotary switch I is subject to wide variation. In the unit illustrated, the actuating shaft I08 rotates a disk I I0 of insulation material on the periphery of which are mounted contact bridges,24', 40' and .54' for selectively engaging the switch contacts respectively associated therewith.

The switch actuating shaft I08 is adapted to an actuating knob I I2. To provide a simple and effective support for the entire unit, a sleeve H3,

surrounding shaft I08 and secured at one end to the switch body I01, extends through and engages the panel Ill, between a shoulder on the sleeve and a nut H4 thereon:

The various condensers and resistances which may also be mounted upon the unit have, for simplicity, not been illustrated in Figs. 2-5. In general these are sufficiently small to be mounted within the shield cans and are preferably so invention provides a multi-band inductance unit that is small, compact, electrically eflicient and subject to close production control, that may readily be made up for different sets of bands by suitably proportioning the electrical characteristics of the apparatus of which it is constituted; that may be connected and tested as an independent unit; that may easily be mounted and removed from a receiver chassis, the electrical connections to be made between it and the receiver chassis being few in number and relatively simple; and one that may easily have its adjustable elements adjusted, if necessary, after installation of the unit in the receiver chassis.

While I have described what I at present consider the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What is claimed is:

1. In a multi-band radio receiver having a plurality, of tunable stages; a compact, multi-band inductance unit comprising; rotary switching mechanism including an actuating shaft and a plurality of contacts disposed about said shaft,

least one for each of the stages of the receiver; a group of inductance elements for each of the stages of the receiver the inductance elements of each of said groups being non-inductively related to the inductance elements of the other of said groups, each group including a plurality of inductance elements having different inductance values for operation over the several bands of the receiver, said groups of inductance elements being mounted with their axes parallel to the axis of said shaft and being angularly disposed about the axis of said shaft at substantially equal radial distances, said inductance elements of each of said groups being similarly disposed with respect to said axis, and axially spaced along said axis, said groups of inductance elements having terminals in proximity to their respective groups of 1 said shaft, said contacts comprising a plurality of groups, at least one for each of the stages of the receiver; a group of inductance elements for each of the stages ofrthe receiver the inductance elements of each of said groups being non-inductively related to the inductance elements of the other of said groups, each group Including a. plurality of inductance elements having diflerent inductance values for operation over the several bands of the receiver, said groups of inductance elements being supported from said switching mechanism. with their axes parallel to the axis of said shaft and being angularly disposed about ,the axis of said shaft at substantially equal radial distances, said inductance elements of each of said groups being similarly disposed with respect v p to said axis and axially spaced along said axis,

' plurality of contacts disposed about said shaft, 7

said groups of inductance elements having terminals in proximity to their respective groups of contacts; and short and-substantially linear connections between the terminals of each group of,

inductance elements and its respective group of contacts, said unit including provisions suitable for detachably engaging a supporting panel.

' 3. In a multi-band radio receiver having a plurality of tunable stages; a compact, multi-band inductance unit comprising; rotary switching mechanism including an actuating shaft and a said contacts comprising a plurality of groups, at least one for each of the stages of the receiver; a group of inductance elements for each of the stages of the receiver, each group including a j plurality of inductance elements having diflerent inductance values for'operation' over the several bands of the receiver, said inductance elements being mounted with their axes parallel to the axis of said shaft, a plurality of said inductance a elements being angularly disposed about the axis of said shaft at substantially equal radial distances, others of said inductance elements being similarly disposed with respect to said axis, but

axially displaced from said last-mentioned inductance elements, said groups of inductance elements having terminals in proximity to their respective groups of contacts; short and substantially linear connections between the terminals of each group of inductance elements and its respective group of contacts, a shield can individual to the group of inductance elements of each of the stages, and adjustable trimmer condensers for the several inductance elements of each group mounted within the respective shield can, said shield cans' beingapertured to provide access' for adjustment of said trimmer condensers, all such apertures being accessible from a given side ofv said unit.

4. In a multi-band radio receiver having a plu rality of tunable stages: a compact, interchangeable, multi-band inductance unit comprising; a supporting shield plate; a rotary switch supported therefrom at one side and including an actuating shaft and a plurality of groups of contacts dis- Posed about said shaft, one group for each of the stages of the receiver; an assembly of inductance elements for each of the stages of the receiver,

said unit including provisions suitable for de-.

tachably engaging a supporting panel.

.5.- In a multi-band radio receiverhaving a plurality of tunable stages a compact, ininarchange able, multi-band inductance unit comprising; a

' supporting structure; a. rotary switch supported therefrom .and including an actuating shaft and a plurality of groups of contacts disposed about said shaft, one group for each of the stages of the receiver; an assembly of inductance elements for each of the stages of the receiver, each as-- sembly including a plurality of coaxial inductance elements having different inductance values for.

operation over the several bands of the receiver, said inductance assemblies being supported from said structure with terminals individually in proximity to said groups of contacts and with their axes parallel'to each other; short and substantially linear connections between the terminals of each assembly and its proximate group of contacts; a separate shield can foreach inductance assembly supported from said structure; andadjustable trimmer condensers for the several inductance elements of each inductance assembly mounted within the shield can thereof along a line parallel to the axis thereof, the several shield cans being apertured along lines parallel to the axes of said assemblies to provide access for adjustment of said trimmer condensers with all such apertures facing in onie direction, certain of said assemblies being positioned rearwardly relative to the direction in which said apertures faces and staggered relative to those forward in the .direction in which said apertures face, the latter being spaced to provide access to the apertures of'those behind, said unit including provisions suitable for detachably engaging a supporting panel. a

6. In a multi-band radio rec'eiver having a plurality of tunable stages: a compact, interchangeable, multi-band inductance unit comprising; a supporting shield plate; a single deck rotary switch supported therefrom at one sideand including a switch body, an actuating shaft perpendicular to said body and a plurality of groups of contacts, one group for each of the stages of the receiver, said switch. body being parallel to the plane of said shield plate and said groups of contacts beingsymmetrically disposed on said switch body about said shaft; an assembly of inductance elements for each of the stages of the receiver, each assembly including a plurality of coaxial inductance elements having difierent inductance values for operation over the'several bands of the receiver; a plurality of shield cans; one for each of said inductance assemblies, secured to said shield plate on the side thereof opposite said switch and so that their longitudinal axes are perpendicular to the plane of said shield plate? each of said inductance assemblies being supported in and by its associated shield can with.

terminals in proximity to one of said groups of contacts, said shield plate having apertures through which said terminals extend; short and substantially linear connectionsbetween the terminals of each assembly and its proximate group of contacts; trimmer condensers for the several inductance elements of each inductance assembly mounted within the shield can of the associated assembly along a line parallel to the axis thereof, the several shield cans being apertured along lines parallel to the axes of said assemblies to provide access to the adjustable elements of said trimmer condensers, all such apertures being faced in one direction and all said assemblies being so staggered-that access may be had to the adjustable elements of allthe trimmer cond'ensers from one side of said unit; and means secured to said switch for-detachably mounting said unit upon a supporting panel.

WAL'I'ER, LYONS, 

